It is previously known to mount optoelectronic components so-called transistor casings. A commonly used such casing comprises a round base, on one plane surface of which one several optoelectronic semiconductor elements is or are arranged. After mounting of the semiconductor element or the semiconductor elements on the base, a similarly round housing is fitted over the base and connected thereto, for example by welding the joint. In connection with casings of this kind, there must be a certain play between the housing and the base. This makes it possible for the position of the housing relative to the base to be changed in an uncontrolled manner between the fitting of the housing on the base and the subsequent welding of the housing to the base. In, for example, such optoelectronic components which comprise a plurality of semiconductor elements with separate light openings or lenses, a rotation of the housing relative to the base, after the fitting of the housing in the desired position, means that the function of the component is reduced or that the component is rendered incapable of functioning. Also in case of components which, in principle, are rotationally symmetrical with one single centrally arranged semiconductor element and with one centrally arranged light opening or lens in the housing, an accurate centering of the housing in relation to the base is often required. Because of a play between the housing and the base, a displacement of the position of the housing relative to the base may easily occur between the fitting of the housing and the subsequent welding to the base. This makes it impossible to attain the desired accurate centering.
For the above reasons, the manufacture of components of the kind described above has either required extra time- and cost-demanding manufacturing stages to ensure the desired relative position between the housing and the base, or the manufacture has resulted in a high percentage of defective components.
Certain optoelectronic components comprise a light-emitting semiconductor element for emitting light to the surroundings as well as a light-receiving element for receiving light from the surroundings. In this type of components, it is of the utmost importance that direct radiation between the light-emitting and the light-receiving semiconductor elements is eliminated, and to attain a rational and economical manufacture it is of importance that this direct radiation can be eliminated in a manner which is both simple and favourable from the manufacturing point of view.
Certain other types of optoelectronic components, so-called optocouplers, comprise a light-emitting and a light-receiving semiconductor element, between which signals are transmitted optically to avoid a galvanic connection between the circuits to which the two semiconductor elements are connected. In such a component, it is a requirement that as large a part as possible of the radiation emitted from the light-emitting semiconductor element reaches the light-receiving semiconductor element. It is known to arrange certain types of reflecting members for controlling the radiation between the two semiconductor elements. However, such members tend to increase the complexity and the manufacturing cost of a component, and it is desirable that the desired control of the radiation can be made in the simplest and economically most favorable way.
Certain other types of optoelectronic components are intended for bidirectional signal transmission, for example through an optical fiber. A typical such component comprises a light-emitting semiconductor element and a light-receiving semiconductor element, which respectively emit and receive optical radiation through a common opening or lens in the housing. In this type of components there are problems in obtaining the required screening of direct radiation between the semiconductor elements as well as in causing emitted light from the light-emitting semiconductor element to be passed out through the common opening or lens in the desired direction and with a high efficiency while at the same time light falling against the component is passed with good efficiency to the light-receiving semiconductor element. Attaining these objectives at the same time has proved to be difficult and to give rise to complicated and hence uneconomical solutions.